Heat oven to 350 F.
In large mixer bowl cream butter or margarine, sugar and vanilla.
Add eggs: beat well. Combine flour and baking soda;
add alternately with chocolate syrup to creamed mixture.
Stir in 1 c. peanut butter chips;
reserve remaining 1 c. chips for frosting.
Pour batter into greased 13x9x2-inch pan; bake 30 to 35 minutes.
Cool; frost with Peanut Butter Brownie Frosting.
Cut into 24 squares.

Peanut Butter Brownie Frosting:
Combine 1/3 c. sugar, 1/4 c. evaporated milk
and 2 tbs. butter in a small saucepan.
Stir over medium heat until mixture comes to full boil;
remove from heat.
Quickly stir in reserved 1 c. Reese's Peanut Butter Chips
until melted: add 1 tsp. vanilla.
Beat to spreading consistency.